1. Field of the Invention
The present invention relates to an adjustable tensioning mechanism and more particularly, to an adjustable force idler pulley and belt mechanism for increasing the tension of a drive belt used in attachment with a lawn mower.
While the present invention can be used in a wide variety of belt-driven applications, the invention will be described primarily with its application as a foot adjustable tensioning mechanism for use with a commercial walk-behind mower.
2. Description of the Related Art
The present invention contemplates a new and improved adjustable force idler pulley and belt which is simple in design, effective in use, and overcomes the following difficulties and others while providing better and more advantageous overall results.
Motor vehicles have used drive belts in association with pulleys as a well known means of transferring power from a central drive unit. Typically, the power is transferred from a central power unit along several pulleys and drive belts. In lawn mowers the central drive unit is the engine which transmits power to the drive wheels and to the cutter assembly.
Belts are used in many household, automotive and industrial applications as a power transmission element. In the present invention a belt is used to transmit power from a motor to a drive mechanism of a walk-behind lawn mower. Typically a power transmission belt is wrapped around a driver pulley and a driven pulley.
One disadvantage of using drive belts is that they tend to stretch under constant tensile forces. Over time this results in a lengthening of the belt and a corresponding reduction of power transferred. Traditionally, these belts are prevented from dislocation or slippage relative to a pulley by belt guards and the tension of the belt. The idler pulley is spring-loaded in a direction transverse to the rotating belt. This arrangement increases the tension on the belt to prevent the belt from slipping and being thrown off the belt wheel. However, when the belt slackens it undergoes excessive wear due to slippage and can fall off the pulley under this traditional idler pulley system. Drive belts require constant monitoring with means available to readily and efficiently adjust belt tension.
Another disadvantage of using drive belts is that they tend to slip when becoming wet such as when the mower is used in rainy or dew conditions. This slippage due to rainy conditions compounds the previously described problems of slippage due to wear. The combination of slippage due to wear and slippage due to wet conditions further diminishes the use of the belt and the ability to use the mower in various conditions.
When using a walk-behind mower in rough conditions, the operator typically needs to increase the power to the driven wheels. Often, the mower gets stuck in rough or uphill conditions requiring more power to be supplied to the driven wheels than is available. In such cases the operator has to push or pull the mower from the entrapped area. The drive belt slips or otherwise cannot provide the driven wheels of the mower the required force to move.
In a walk-behind mower, the operator traditionally controls movement of the mower by hand control levers located on the right and left side of the mower. Other means to increase the belt tension have included the operator to push or pull a device located outside of the operators handle bars having the motion control hand levers. In order to increase the tension between the belt and the pulley the operator must remove one hand from the handlebars and pull a traction/tensioning device to increase the belt tension.
Other known belt tensioning adjustment mechanisms can be cumbersome, difficult to operate and may require hand tools to change or adjust.